Certain medical procedures require a bodily fluid pressure to be measured and monitored. For example, it is often desirable to measure and monitor an amniotic fluid pressure in a neonatal procedure, or to measure and monitor a pressure of an intracranial fluid in a neurological procedure. Most commonly, it is desirable to measure and monitor a blood pressure at a selected internal location in a patient. For example, in order to monitor the heart function in a patient, it is often advantageous to measure and monitor the blood pressure within the chambers of the heart. In all of the foregoing examples, the bodily fluid pressure is measured and monitored with a medical pressure transducer that is generally spaced apart from the body of the patient and fluidly coupled to a selected location in the patient's body by a catheter that is introduced into the body and positioned in a bodily region of interest. The fluid pressure in the selected region is then communicated to the medical transducer through the catheter.
In general, to measure and monitor a selected bodily pressure, the catheter is first filled with a sterile saline solution and de-bubbled. A hypodermic needle is then inserted into a selected portion of the body, such as a blood vessel. The catheter is then threaded through the hypodermic needle and directed into the body until the tip of the catheter is positioned at a location where the bodily pressure measurement is desired. When the catheter is suitably positioned, the needle may be removed, and the opening may be taped to secure the catheter tip at the selected location. The opposing end of the catheter is coupled to pressure tubing that is also similarly filled with a saline solution, which is then coupled to the pressure transducer. The pressure transducer may also be coupled to an external monitoring device and/or other devices, such as a visual display that permits the bodily pressure waveform of the patient to be viewed directly.
In the foregoing description, it is apparent that the various components of the bodily pressure measurement apparatus are exposed to the bodily fluid of the patient. Heightened concerns relating to the transmission of blood-borne pathogens, including hepatitis B virus (HBV) and the human immunodeficiency virus (HIV) have spurred the development of medical instruments, devices, and other items that are disposable to minimize the likelihood of transmitting infectious diseases between patients. Accordingly, disposable devices that are configured to measure and/or monitor a bodily pressure have been developed. Such disposable devices typically include a pressure sensor having an attached electrical cable, and an attached plastic housing that includes a valve device and associated tubing, which are generally fabricated as a single unit and provided to a medical provider as a single unit in a sterile package. Since a disposable pressure sensing assembly is intended to be used to measure and/or monitor a bodily pressure in a single patient and discarded afterwards, the cost associated with the use of such disposable assemblies may be relatively high. In particular, the pressure transducer and the associated electrical cable generally constitute the most costly components of the disposable assembly.
What is needed is a pressure sensing assembly for use in a patient monitoring system having a disposable first portion that is exposed to the patient-contacting fluid path, and a reusable second portion that remains isolated from the patient-contacting fluid path that includes the relatively costly components, such as the pressure transducer and the associated electrical cable.